A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
about the Ask Ubuntu Clean Up meant to clean up the site
When the question deals with the format of the answers posted on Ask Ubuntu.
an editable page that briefly summarizes the topic of the tag and that may provide links to existing questions that are often useful to many people. Questions about the content of the …
used by moderators (for EOL notices) or by anyone for discussions about handling posts about EOL versions of Ubuntu.